If you’ve ever frantically googled “How many hours of sleep do I really need?” after a particularly disruptive night, you’ve probably come across the same answer time and time again.

For decades, the golden number has been eight. Eight hours of blissful slumber to keep our bodies and brains functioning at their peak. However, major new research from the University of Cambridge and Shanghai’s Fudan University is challenging the widely held belief.

According to their scientists, who looked at the sleep habits of almost 500,000 adults between the ages of 38 and 73, we should actually be aiming for seven hours’ sleep – at least from our late-30s onwards.

“For every hour that you moved away from seven hours, you got worse. It’s very clear that the processes that go on in our brain during sleep are very important for maintaining our physical and mental health,” said lead researcher Professor Barbara Sahakian, from Cambridge University’s department of psychiatry.

Our sleep is something we’re constantly trying to hack, whether it’s banking it, catching up on it, having a lie-in or rising early.

Sleeplessness is an increasing problem, particularly since the pandemic – 36% of UK adults report already struggling to get to sleep at least once a week, a figure that only increases when variables like hot weather, stress and daylight savings come into play.

The current National Sleep Foundation guidelines recommend that most adults aged between 18 and 64 get seven to nine hours of shut-eye per night, but while it may seem counter-intuitive, when it comes to sleep, more isn’t necessarily better. 

The Cambridge researchers discovered that both too much and not enough sleep were linked to mental health problems and “worse cognitive performance”. So if you’ve ever felt groggy and lethargic after a long stretch in bed, that could be why.

The study also found that consistency mattered – so it’s no good getting nine hours one night then six the next.

The study isn’t the first time the idea of eight hours sleep has been brought into question. According to sleep scientist Daniel Gartenberg in an interview with Quartz, even if you’re in bed for eight hours, you’re probably only asleep for just over seven.

“In order to get a healthy eight hours of sleep, which is the amount that many people need, you need to be in bed for 8.5 hours,” said Gartenberg. “The standard in the literature is that healthy sleepers spend more than 90% of the time in bed asleep, so if you’re in bed for eight hours, a healthy sleeper might actually sleep for only about 7.2 hours.”

It seems we really should be focusing on quality and depth over quantity, after all.

For more tips on how to sleep better, you can read more Strong Women content here.

Images: Getty